CN101857544B - Synthesis method of herbicide 2, 4-dichlorphenoxyacetic acid - Google Patents
Synthesis method of herbicide 2, 4-dichlorphenoxyacetic acid Download PDFInfo
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Abstract
The invention relates to a synthesis method of herbicide 2, 4-dichlorphenoxyacetic acid, which comprises the following steps that: under the existence of weak base and the effect of sodium iodide and phase transfer catalyst, 2, 4-dichlorophenol is condensed with monochloroacetone through Williamson to obtain 2, 4-dichlorophenoxy acetone; the obtained 2, 4-dichlorophenoxy acetone is reacted and acidified in sodium hypochlorite solution to finally obtain 2, 4-D. With the method, the free phenol content in the product can be effectively controlled below the national standard, the discharge of the phenol-contained waste water can be reduced, and the synthesis method is simple and convenient to operate and has good product quality and small environmental pollution.
Description
Technical field
The present invention relates to a kind of synthetic method of weedicide 2,4 dichlorophenoxyacetic acid.
Background technology
2,4-D is 2, the 4-dichlorphenoxyacetic acid, it is one of most popular weedicide, can the crop Tanakas such as wheat, rice, corn, sugarcane except the broadleaf weeds such as lamb's-quarters, amaranth and the budding period gramineous weeds, when lower concentration, can be used as plant-growth regulator, be used for preventing the fruit drop such as tomato, cotton, pineapple and form s.m.p fruit etc., and the functions such as lodging-prevention, promotion increasing production of rice and precocity are arranged, also can be used as mould inhibitor.
2,4-D sterling is white crystals, and solubleness is very little in the water, is soluble in the organic solvents such as ethanol, benzene, usually is processed to the use such as liquor, pulvis, emulsion of sodium salt, ammonium salt or ester class.
The traditional synthesis of 2,4-D is comparatively ripe, and cost is also lower, mainly contain two kinds of synthesis techniques: the one, phenol chlorination etherification method, i.e. phenol first chlorination under molten state, the intermediate 2 of generation, the 4-chlorophenesic acid again with chloroacetate reaction, obtain product by the williamson etherificate; The 2nd, phenol etherificate chlorination process, namely phenol first with the Mono Chloro Acetic Acid etherificate, the intermediate of generation again chlorination obtains 2,4-D.These two kinds of methods are removed in the process of aldehydes matter in production process and aftertreatment, can produce a large amount of phenolic wastewater, and the also bad control of content of free phenol in the product.The free phenol residual quantity is too much in the product, as agricultural chemicals very adverse influence will be arranged to it, and it will have influence on normal growth and the output of crop, when serious even can cause the death of crop.According to the chemical industry standard HG 3624-1999 of the People's Republic of China (PRC), the content of free phenol answers≤0.3% in the former medicine of 2,4-D.In above synthesis technique, in order to reduce the residual quantity of free phenol in the product, the way of processing is exactly recrystallization or wet distillation, and the former can reduce product yield, and increases solvent loss, and latter can produce phenolic wastewater, and certain defect is arranged.
Summary of the invention
The object of the present invention is to provide a kind of content that can effectively reduce free phenol in the product, reduce the phenolic wastewater discharging, and obtain the synthetic method of high-quality weedicide 2,4 dichlorophenoxyacetic acid.
The weedicide 2 that the present invention proposes, the synthetic method of 4-D, synthetic route is as follows:
Concrete steps are as follows:
(1) with 2, the 4-chlorophenesic acid is raw material in the presence of the weak base, under sodium iodide and the phase-transfer catalyst effect, obtain 2,4 dichloro benzene oxygen benzylacetone with Mono Chloro acetone through the williamson etherification reaction, adopt in solid-liquid two phase reaction or the liquid-liquid two phase reaction any;
The solid-liquid two phase reaction: take inoganic solids as alkali, add sodium iodide and phase-transfer catalyst, be warming up to 50～80 ℃, stir a lower oxyacetone and the solvent of adding, after being added dropwise to complete, continuation reaction 2.5～3.5 hours, products therefrom filters, desolventizing, rectifying purifying; Wherein: the add-on of phase-transfer catalyst is 1～10mol% of 2,4 dichloro phenol, and the mol ratio of alkali and 2,4 dichloro phenol is 1: 1～3: 1; The mol ratio of 2,4 dichloro phenol and Mono Chloro acetone is 1: 1～1: 2.The add-on of sodium iodide is 1～5mol% of 2,4 dichloro phenol.，
Liquid-liquid two phase reaction: in the presence of the alkaline aqueous solution, under sodium iodide and the phase-transfer catalyst effect, be warming up to 50～80 ℃, stir lower add Mono Chloro acetone and solvent, after being added dropwise to complete, continue reaction 2.5～3.5 hours, products therefrom filters, static rear branch vibration layer, the organic layer washing, desolventizing, rectifying purifying; Wherein: the add-on of phase-transfer catalyst is 1～10mol% of 2,4 dichloro phenol, and the mol ratio of weak base and 2,4 dichloro phenol is 1: 1～3: 1; The mol ratio of 2,4 dichloro phenol and Mono Chloro acetone is 1: 1～1: 2; The add-on of sodium iodide is 1～5mol% of 2,4 dichloro phenol.
(2) step (1) gained 2,4 dichloro benzene oxygen benzylacetone and solvent are joined in the alkaline aqueous solution of clorox, stir, reacted 5～6 hours under ℃ temperature of room temperature～50, it is 2～3 that water layer is acidified to PH, filters, and recrystallization namely gets required product; Wherein: the mol ratio of clorox and 2,4 dichloro benzene oxygen base propionic acid is 4: 1-5: 1.
Among the present invention, in the step (1) alkali described in the solid-liquid two phase reaction be in yellow soda ash, salt of wormwood or the sodium bicarbonate any, described phase-transfer catalyst adopts the crown ether compounds such as 18-hat-6 or 15-hat-5; Or PEG-400, PEG-600, the quaternary ammonium compounds such as the polyoxyethylene glycol such as PEG-800 (PEG) compounds, triethyl benzyl ammonium salt, trimethylammonium hexadecyl ammonium salt or 4-butyl ammonium; Described solvent adopts acetone, butanone, tetrahydrofuran (THF), dioxane, acetonitrile, among DMF or the DMSO etc. any.
Among the present invention, alkaline aqueous solution described in liquid in the step (1)-liquid two phase reaction be in aqueous sodium carbonate, wet chemical or the sodium bicarbonate aqueous solution any; The concentration of described alkaline aqueous solution is 50% or saturated solution; Phase-transfer catalyst is the most suitable with quaternary ammonium compound, and such as triethyl benzyl ammonium salt, trimethylammonium hexadecyl ammonium salt or 4-butyl ammonium etc. all can.Described solvent adopts hexanaphthene, and the alkane aromatic hydrocarbon solvents such as benzene or toluene are advisable.
Among the present invention, solvent described in the step (2) be in Isosorbide-5-Nitrae-dioxane, tetrahydrofuran (THF) or the acetonitrile etc. any.
Among the present invention, the add-on of phase-transfer catalyst is 3～5mol% of 2,4 dichloro phenol in the step (1).
Among the present invention, the mol ratio of 2,4 dichloro phenol and Mono Chloro acetone is 1: 1.2～1: 1.5 in the step (1).
Among the present invention, alkaline aqueous solution described in the step (2) adopts NaOH, and the mol ratio of NaOH and 2,4 dichloro benzene oxygen benzylacetone is 3: 1～5: 1.
Employed alkali is the weak base such as yellow soda ash, salt of wormwood, sodium bicarbonate in the step of the present invention (1), and sodium hydroxide though the highly basic such as potassium hydroxide also can use, still causes the side reaction that Mono Chloro acetone changes pyruvic alcohol into easily.React completely for making, need to increase the consumption of Mono Chloro acetone.In the solid-liquid phase reaction, above-mentioned inorganic compound solid needs it is ground into Powdered before use, to guarantee that reaction smoothly.And in the liquid-liquid phase reaction, use be their aqueous solution, but require its concentration to want high, with 50% or saturated solution be advisable.
The temperature of reaction of step among the present invention (1) can be from the room temperature to the reflux temperature.Though room temperature reaction control is convenient, speed of response is too slow, and suitable heating is necessary, but the reaction under the reflux conditions brings inconvenience to operation after all.Therefore the most appropriate to be controlled at 50～80 ℃ reaction.
Among the present invention, using the chlorine bleach liquor to replace leading in the water the hypochlorous method of preparation of chlorine in the step (2) reacts, reaction has higher requirement to the content of available chlorine among the chlorine bleach liquor, and content can obviously affect reaction yield, and available chlorine content answers 〉=20%.React completely for making, it is excessive that clorox needs.The mol ratio of it and 2,4 dichloro benzene oxygen benzylacetone is controlled at 4～5: 1.
Among the present invention, the reaction needed of step (2) is carried out under alkaline condition.The pH value of reaction system is very large on the speed of response impact, and the pH value is high, and speed of response is then fast.So will add the alkalescence of certain NaOH conditioned reaction system in the reaction.And reaction needs with the acid neutralization after finishing, and too many alkali can be made troubles to aftertreatment.Therefore the mol ratio of NaOH and 2,4 dichloro benzene oxygen benzylacetone preferably is controlled at 3～5: 1.The solvent that uses in the reaction requires the chlorine bleach liquor stablely, and has certain water-solublely, is conducive to reaction and carries out smoothly.Be advisable with Isosorbide-5-Nitrae-dioxane, tetrahydrofuran (THF), acetonitrile etc.Temperature of reaction is controlled at ℃ interval, room temperature～50 and carries out.
The present invention is take 2,4 dichloro phenol as raw material, generates intermediate 2,4 dichloro benzene oxygen benzylacetone with Mono Chloro acetone through the williamson reaction first, again through haloform reaction obtain 2,4-D.In the williamson reaction, except adding sodium iodide, the present invention has also increased phase-transfer catalyst, has effectively solved the problems such as two phase reaction speed is slow, yield is low.And residual phenol is easy to separate with 2,4 dichloro benzene oxygen benzylacetone after the reaction end.As adopting the solid-liquid phase mode to react, residual phenol can be filtered easily with inoganic solids with the form of phenates and remove.The 2,4 dichloro benzene oxygen benzylacetone that reaction generates also will be further purified through fractionation.And the reaction of liquid-liquid two-phase, phenates also is easy to separate with organic phase in water layer.In the water layer and after, free chlorophenesic acid can be recycled.Prepare 2,4-D with the 2,4 dichloro benzene oxygen benzylacetone behind the purifying, its free phenol content can be controlled at below the GB effectively.The characteristics such as present method has easy and simple to handle, and quality product is high, and environmental pollution is little.
Embodiment
Further specify the present invention below by embodiment.
Embodiment 1
(1) 2,4 dichloro benzene oxygen benzylacetone is synthetic
In the 1000mL there-necked flask, add 58g (0.55mol) yellow soda ash, 81g (0.5mol) 2,4 dichloro phenol, 6.0gPEG-400,1.2g sodium iodide and 200mL acetonitrile are warming up to 70 ℃.Slowly drip the mixed solution of 55g (0.6mol) Mono Chloro acetone and 50mL acetonitrile under the high degree of agitation, drip off rear continuation reaction 3 hours.Filter after being chilled to room temperature, the filtrate desolventizing, the cut of 100～102 ℃/1mmHg is collected in fractionation, gets 2,4 dichloro benzene oxygen benzylacetone 101g, purity＞99%, productive rate 92%.
(2) 2,4 dichlorophenoxyacetic acid is synthetic
In the 500mL there-necked flask, add the chlorine bleach liquor of 150g available chlorine 〉=20%, 20g sodium hydroxide, room temperature also stirs the lower 22g of dropping (0.1mol) 2, the solution of 4-Dichlorophenoxy benzylacetone and 40mL Isosorbide-5-Nitrae-dioxane drips off rear continuation and stirs half an hour.Be warming up to about 5 hours of 40 ℃ of reactions, add entry and make insolubles entirely molten.Then add sodium sulfite solution and stir, until water layer no longer makes starch KI test paper become blue.Water layer drips 50% sulphuric acid soln while stirring under cooling, be acidified to pH 2～3.Filter, crude product gets 2,4 dichlorophenoxyacetic acid 16g, content 98%, productive rate 69% with 30% aqueous ethanolic solution recrystallization.
Embodiment 2
(1) 2,4 dichloro benzene oxygen benzylacetone is synthetic
In the 1000mL there-necked flask, add 65g (0.6mol) yellow soda ash, 81g (0.5mol) 2,4 dichloro phenol, the 2.5g tetrabutylammonium chloride, 1.2g sodium iodide and 200mL acetone are warming up to 50 ℃.Slowly drip the mixed solution of 55g (0.6mol) Mono Chloro acetone and 50mL acetone under the high degree of agitation, drip off rear continuation reaction 3 hours.Filter after being chilled to room temperature, filtrate desolventizing, fractionation obtain 2,4 dichloro benzene oxygen benzylacetone 99g, productive rate 90%.
(2) 2,4 dichlorophenoxyacetic acid is synthetic
In the 500mL there-necked flask, add the chlorine bleach liquor of 150g available chlorine 〉=20%, 15g sodium hydroxide, room temperature also stirs the lower solution that drips 22g (0.1mol) 2,4 dichloro benzene oxygen benzylacetone and 40mL tetrahydrofuran (THF), drips off rear continuation and stirs half an hour.Be warming up to about 6 hours of 40 ℃ of reactions, add entry and make insolubles entirely molten.Then add sodium sulfite solution and stir, until water layer no longer makes starch KI test paper become blue.Water layer drips 15% hydrochloric acid soln while stirring under cooling, be acidified to pH2～3.Filter, crude product gets 2,4 dichlorophenoxyacetic acid 14g, productive rate 65% with 30% aqueous ethanolic solution recrystallization.
Embodiment 3
(1) 2,4 dichloro benzene oxygen benzylacetone is synthetic
In the 1000mL there-necked flask, add the 300mL saturated aqueous sodium carbonate, 81g (0.5mol) 2, the 4-chlorophenesic acid, 2.5g tetrabutylammonium chloride, 1.2g sodium iodide and 200mL toluene are heated to 60 ℃, drip the solution of 64g (0.7mol) Mono Chloro acetone and 80mL benzene under the high degree of agitation, drip off rear continuation reaction 5 hours.Reaction mixture is down to room temperature, and static rear branch vibration layer, organic layer are used respectively 100mL10% dilute hydrochloric acid solution and water (100mL * 2) washing.With removing benzene behind the anhydrous sodium sulfate drying, fractionation gets 2,4 dichloro benzene oxygen benzylacetone 95g, productive rate 88%.
(2) 2,4 dichlorophenoxyacetic acid is synthetic
In the 500mL there-necked flask, add the chlorine bleach liquor of 180g available chlorine 〉=20%, 15g sodium hydroxide, room temperature also stirs the lower solution that drips 22g (0.1mol) 2,4 dichloro benzene oxygen benzylacetone and 40mL dioxane, drips off rear continuation and stirs half an hour.Be warming up to about 6 hours of 40 ℃ of reactions, add entry and make insolubles entirely molten.Then add sodium sulfite solution and stir, until water layer no longer makes starch KI test paper become blue.Water layer drips 15% hydrochloric acid soln while stirring under cooling, be acidified to pH2～3.Filter, crude product gets 2,4 dichlorophenoxyacetic acid 14g, productive rate 65% with 30% aqueous ethanolic solution recrystallization.
Claims (7)
1. the synthetic method of a weedicide 2,4 dichlorophenoxyacetic acid is characterized in that concrete steps are as follows:
(1) with 2, the 4-chlorophenesic acid is raw material in the presence of the weak base, under sodium iodide and the phase-transfer catalyst effect, obtain 2,4 dichloro benzene oxygen benzylacetone with Mono Chloro acetone through the williamson etherification reaction, adopt in solid-liquid two phase reaction or the liquid-liquid two phase reaction any;
The solid-liquid two phase reaction: take inoganic solids as alkali, add sodium iodide and phase-transfer catalyst, be warming up to 50～80 ℃, stir lower Mono Chloro acetone and the solvent of adding, after being added dropwise to complete, continuation reaction 2.5～3.5 hours, products therefrom filters, desolventizing, rectifying purifying; Wherein, the add-on of phase-transfer catalyst is 1～10mol% of 2,4 dichloro phenol, and the mol ratio of alkali and 2,4 dichloro phenol is 1: 1～3: 1; The mol ratio of 2,4 dichloro phenol and Mono Chloro acetone is 1: 1～1: 2; The add-on of sodium iodide is 1～5mol% of 2,4 dichloro phenol;
Liquid-liquid two phase reaction: in the presence of the alkaline aqueous solution, under sodium iodide and the phase-transfer catalyst effect, be warming up to 50～80 ℃, stir lower add Mono Chloro acetone and solvent, after being added dropwise to complete, continue reaction 2.5～3.5 hours, products therefrom filters, static rear branch vibration layer, the organic layer washing, desolventizing, rectifying purifying; Wherein, the add-on of phase-transfer catalyst is 1～10mol% of 2,4 dichloro phenol, and the mol ratio of weak base and 2,4 dichloro phenol is 1: 1～3: 1; The mol ratio of 2,4 dichloro phenol and Mono Chloro acetone is 1: 1～1: 2; The add-on of sodium iodide is 1～5mol% of 2,4 dichloro phenol;
(2) step (1) gained 2,4 dichloro benzene oxygen benzylacetone and solvent are joined in the alkaline aqueous solution of clorox, stir, reacted 5～6 hours under ℃ temperature of room temperature～50, it is 2～3 that water layer is acidified to pH, filters, and recrystallization namely gets required product; Wherein: the mol ratio of clorox and 2,4 dichloro benzene oxygen benzylacetone is 4: 1～5: 1.
2. weedicide 2 according to claim 1, the synthetic method of 4-dichlorphenoxyacetic acid, it is characterized in that in the step (1) alkali described in the solid-liquid two phase reaction be in yellow soda ash, salt of wormwood or the sodium bicarbonate any, described phase-transfer catalyst adopts crown ether compound, polyoxyethylene glycol compounds or quaternary ammonium compound; Described solvent adopts acetone, butanone, tetrahydrofuran (THF), dioxane, acetonitrile, among DMF or the DMSO any.
3. weedicide 2 according to claim 1, the synthetic method of 4-dichlorphenoxyacetic acid, it is characterized in that alkaline aqueous solution described in liquid in the step (1)-liquid two phase reaction be in aqueous sodium carbonate, wet chemical or the sodium bicarbonate aqueous solution any; The concentration of described alkaline aqueous solution is 50% or saturated solution; Phase-transfer catalyst adopts quaternary ammonium compound, and described solvent adopts hexanaphthene, in benzene or the toluene any.
4. the synthetic method of weedicide 2,4 dichlorophenoxyacetic acid according to claim 1, it is characterized in that solvent described in the step (2) be in Isosorbide-5-Nitrae-dioxane, tetrahydrofuran (THF) or the acetonitrile any.
5. the synthetic method of weedicide 2,4 dichlorophenoxyacetic acid according to claim 1 is characterized in that the add-on of phase-transfer catalyst in the step (1) is 3～5mol% of 2,4 dichloro phenol.
6. the synthetic method of weedicide 2,4 dichlorophenoxyacetic acid according to claim 1 is characterized in that the mol ratio of the middle 2,4 dichloro phenol of step (1) and Mono Chloro acetone is 1: 1.2～1: 1.5.
7. the synthetic method of weedicide 2,4 dichlorophenoxyacetic acid according to claim 1 is characterized in that alkaline aqueous solution described in the step (2) adopts NaOH, and the mol ratio of NaOH and 2,4 dichloro benzene oxygen benzylacetone is 3: 1～5: 1.
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| CN102336654A (en) * | 2011-07-14 | 2012-02-01 | 大连化工研究设计院 | Chloration method for phenoxyacetic acid and derivatives thereof |
| CN107641074A (en) * | 2017-09-19 | 2018-01-30 | 常州亚邦制药有限公司 | The production method of mexiletine hydrochloride |
| CN113121335A (en) * | 2021-04-16 | 2021-07-16 | 宁夏格瑞精细化工有限公司 | Preparation method of 2, 4-dichlorophenoxyacetic acid |
| CN117142946A (en) * | 2023-10-27 | 2023-12-01 | 山东海化集团有限公司 | Clean purification process of 2, 4-dichlorophenoxyacetic acid |
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| CN1234177A (en) * | 1998-05-01 | 1999-11-10 | 日本农药株式会社 | Amino-acetonitrile derivative, pesticides containing same for farm and gardening and use thereof |
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| CN1234177A (en) * | 1998-05-01 | 1999-11-10 | 日本农药株式会社 | Amino-acetonitrile derivative, pesticides containing same for farm and gardening and use thereof |
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